Welcome to Medical News Today

Healthline Media, Inc. would like to process and share personal data (e.g., mobile ad id) and data about your use of our site (e.g., content interests) with our third party partners (see a current list) using cookies and similar automatic collection tools in order to a) personalize content and/or offers on our site or other sites, b) communicate with you upon request, and/or c) for additional reasons upon notice and, when applicable, with your consent.

Healthline Media, Inc. is based in and operates this site from the United States. Any data you provide will be primarily stored and processed in the United States, pursuant to the laws of the United States, which may provide lesser privacy protections than European Economic Area countries.

By clicking “accept” below, you acknowledge and grant your consent for these activities unless and until you withdraw your consent using our rights request form. Learn more in our Privacy Policy.

Please accept our privacy terms

We use cookies and similar technologies to improve your browsing experience, personalize content and offers, show targeted ads, analyze traffic, and better understand you. We may share your information with third-party partners for marketing purposes. To learn more and make choices about data use, visit our Advertising Policy and Privacy Policy. By clicking “Accept and Continue” below, (1) you consent to these activities unless and until you withdraw your consent using our rights request form, and (2) you consent to allow your data to be transferred, processed, and stored in the United States.

Get the MNT newsletter

Email an article

You have chosen to share the following article:

How elderberries can help you fight the flu

To proceed, simply complete the form below, and a link to the article will be sent by email on your behalf.Note: Please don't include any URLs in your comments, as they will be removed upon submission.

We do not store details you enter into this form. Please see our privacy policy for more information.

Subchondral bone cysts are sacs of fluid that form inside a person's joints. The cysts occur in the subchondral bone, the layer of bone just under the cartilage.

The subchondral bone acts as a shock absorber in weight-bearing joints, such as the knees, hips, and shoulders. The liquid inside subchondral bone cysts (SBCs) is hyaluronic acid, a component found in synovial fluid, which is the thick substance that lubricates joints, allowing the bones to slide past one another without friction.

Risk factors for SBCs include obesity and smoking, but the precise cause is unknown. Symptoms include joint pain and discomfort. Lifestyle changes help symptom relief and may prevent the formation of other SBCs.

Fast facts on SBCs:

Initially discovered in the 1940s, SBCs are a sign of osteoarthritis (OA).

The exact cause of SBCs is not known.

Engaging in high-impact activities can contribute to injury and damage to the joint and cartilage over time, possibly leading to SBCs.

SBCs are diagnosed using imaging tests, such as X-rays.

What is the link between SBCs and OA?

A swollen joint may be a symptom of a subchondral bone cyst.

Carrying excess weight may be a risk factor for SBC.

Some experts believe that SBCs are a precursor to osteoarthritis (OA), which itself is a painful condition affecting more than 30 million adults in the United States.

OA causes the cartilage and bones within a joint to gradually break down. SBCs are considered one of the four cardinal or key radiological findings for OA.

However, in one large study of 806 people with OA in the knee, SBCs were found in only 30.6 percent of them. Other conditions besides OA, such as rheumatoid arthritis, also cause cysts to form on the bone joints.

Causes

Though the cause is unknown, it is thought SBCs are the result of repeated stress to the bone. This stress is caused by increased pressure from quicker blood flow to the subchondral bone, something that is seen in people with OA.

What are the risk factors?

Certain characteristics and behaviors can increase the risk of developing an SBC. These include:

Sex - women may have a higher risk than men of SBC formation, according to some research.

Heredity - as certain forms of OA may be hereditary, people with a family member with the condition are more likely to develop OA and SBCs.

Joint alignment and shape - abnormal joint shape or alignment can increase friction, leading to greater damage and a higher risk of cyst formation.

Obesity - carrying excess weight puts additional pressure on the joints of the body, increasing the risk of joint problems.

Smoking - tobacco contains chemicals that contribute to cartilage damage. Some research has shown that male smokers with OA experience greater cartilage loss.

Activity and injury - joint injuries increase the risk of joint problems later, including the development of SBCs.

Treatment and management

Low-impact activities may help to treat and manage SBC and OS.

It is recommended that SBCs are not treated directly. Due to the risk of infection, these cysts should not be removed. However, they can regress on their own.

As a result, treatment typically involves making lifestyle changes and providing symptom relief. Some people may benefit from replacing the joint if problems are ongoing or progressive.

Treatments for SBCs include the following:

Nonsteroidal anti-inflammatory drugs (NSAIDs)

These over-the-counter painkillers, such as ibuprofen and aspirin, may reduce symptoms of SBCs. It is always advisable to check with a doctor before taking NSAIDs. Long-term use should be avoided.

Low-impact activities

It may be recommended to choose low-impact activities such as swimming, aqua aerobics, and cycling. These put less pressure on the knees and hips joints than high-impact activities, such as running and jumping, which can exacerbate the symptoms of OS and SBCs and lead to further joint damage over time.

2019 Healthline Media UK Ltd. All rights reserved. MNT is the registered trade mark of Healthline Media. Any medical information published on this website is not intended as a substitute for informed medical advice and you should not take any action before consulting with a healthcare professional.